To clarify the possible function of taste receptors in the development of upper airway reflex apnea, we propose to establish whether chemosensitive fibers in the superior laryngeal nerve innervate epiglottal taste buds. It has been shown that an important afferent neural pathway regulating upper airway reflexes is through chemosensitive fibers in the superior laryngeal nerve. Although a possible role of epiglottal taste buds in mediating the reflexes has been suggested, the biological significance of these taste receptors is not at all clear. Neurophysiological recordings will be made from single superior laryngeal nerve fibers while stimulating the epiglottis of newborn lambs with chemicals. The receptive field of each fiber will be mapped, dissected, and examined histologically; the receptor(s) in each field will be identified. To characterize the chemosensitive response characteristics of superior laryngeal nerve fibers, responses from this nerve will be compared with those recorded from the chorda tympani and glossopharyngeal nerves while stimulating the anterior and posterior tongue (respectively). Responses of the superior laryngeal, chorda tympani, and glossopharyngeal nerves will be recorded while stimulating the epiglottis or tongue with the same sequences of chemicals. Knowledge of differences in the response characteristics of taste buds in different anatomical locations, supplied by different cranial nerves, will perhaps reveal new functions for chemoreceptors that have been previously associated with gustation only. Epiglottal taste buds may mediate the reflex apnea possibly involved in the etiology of the Sudden Infant Death Syndrome.